Electric meter.



No. 643,392. Patented Feb. l3, I900. J. H. BARKER &. J. A. EWING.

ELECTRIC METER.

(Application filed Aug. 14, 1899.)

2 Sheets-Shoet I.

(No Model.)

No. 643,392. Patentod Feb. 13, I900.

J. H. BARKER & J. A. EWING.

ELECTRIC METER.

(Apglication filed Aug. 14, 1899.). N o M n d e I 2 Sheets-Sheet 2.

Unir'rno Breaths JOHN HENRY BARKER AND JAMES ALFRED EWING, OF CAMBRIDGEENGLAND.

ELECTRIC IVi ETER.

SPECIFICATION forming part of Letters Patent No. 643,392, dated February13, 1900. Application filed August 14, 1899. Serial No. 727,188. (Nomodel.)

To whom it may concern:

Be it known we, JOHN HENRY BARKER and JAMES ALFRED EWING, subjects ofthe Queen of England, residing at Cambridge, in the county of Cambridge,England, have invented certain newand useful Improvements in or Relatingto Electric Meters, (for which We have made application for LettersPatent in Great Britain, No. 15,705, dated August 1, 1899,) of which thefollowingis aspecification.

Our invention relates to improvements in electric meters, and hasspecial reference to apparatus incorporated in such meters for thepurpose of indicating the maximum rate of supply of electric current orelectric energy.

In certain well-known types of electric meters the rotation of a disk orother revolving conductor is opposed by the electromagnetic drag betweenit and a magnetic brake consisting of a fixed magnet or magnets inconsequence of the eddy-currents which are generated in the conductor bysuch relative rotation.

, In carrying out our invention we suspend or pivot the magnet ormagnets in such a way that they are allowed to move through a smalldistance against a spring orother suitable controlling force. Thismotion is caused to actuate a pointer or other indicator whichmultiplies the small motion of the magnets and indicates the greatestdrag between the magnets and the disk. We make the spring or othercontrolling force comparatively strong in order that the motion of themagnetpoles may be so small as not to affect the rate of the meter andalso in order that the period of oscillation of the suspended system maybe short. The advantage of this will be readily seen, for if a suddenincrease in the rate of supply tothe meter takes place the suspendedmagnetic brake would tend to swing beyond the position proper to the newrate of supply if its period of oscillation were not short in relationto the time taken by the revolving parts of the meter to acquire theirnew velocity. h This tendency is obviated by making the period of thebrake sufficiently short in relation to the time during which the diskis undergoing acceleration when a current is suddenly applied orsuddenly increased. Further advantages of the strong controlling force,and consequently small movement of the brake, are that there is nonecessity to provide a dash-pot or other means for checking theoscillations, although such means may be provided, if desired, and themagnet may be pivoted ecceutrically to the disk. Again, the small motionof the magnets assists in preventing disturbance of the indicationsthrough the direct effect of the motor-coils in cases where continuouscurrents are used.

In the accompanying drawings, Figure l is a side elevation, partly insection, showing a portion of one construction of meter according tothis invention. Fig. 2 is a plan. Fig. 3 is a front elevation of thesame, parts being removed for the sake of clearness. Fig. 4 shows adetail of the device in elevation in a direction at right angles to Fig.Fig. 5 is a side View illustrating a pawl and ratchet applied to thepointer K of Figs. 1 and 3; and Fig. 6 is a perspective view showing asimilar pawl and ratchet applied to an auxiliary needle, which latterindicates maximum deflection only.

A is a disk of conducting material supported on the axle A and revolvingwhen the meter is in operation between the poles B of magnets B. Thesemagnets B are connected together by a frame or bridge-piece O, to whichthey are secured by clamps or stirruppieces 0 or holes in the magnetsand screws C Slots 0 in the bridge-piece 0 allow for adjustment of thedistance between the poles of the two magnets B. The magnets B arecarried upon an axle D, which passes through the center of thebridge-piece O and is supported so that it is free to turn in thefootstep bearing E and the bracket F. The parts E and F are attached tothe frame of the instrument. The axle D carries an arm G, adj ustablysecured to it by a set-screw G. The set-screw G admits of an adjustmentfor Zero and for the sensitiveness of the instrument. In place ofadjusting by means of the setscrew the arms may be bent for thispurpose. A spring His provided to control the motion of the magnets whenthey turn, owing to the drag between them and the revolving disk A. Thespring I-I may be arranged to relieve the foot-step bearing E of thewhole or a part of the weight of the magnets and is so strong that themagnets can only turn through a [applied to other types of electricmeters, sucli small angle. The extent to which the mag nets 13 turn isindicated upon a scale J by a pointer K, pivoted, as at K, and operatedby the arm G. In order that the extent of the greatest motion of themagnets may be recorded, we provide a light pawl or detent M,

pivoted to an arm 0 forming part of the frame or bridge-piece whichcarries the magnets. The free end of this pawl M passes over thefinely-cut teeth of a rack M, attached to a portion of the frame of theinstrument, and, as shown in Figs. 3 and 4, the magnets are kept intheir position of greatest angular movement until the pawl M isdisengaged from the rack M.

In order that the oscillating system may be securely held and preventedfrom being damaged during transport, holes C are made in the ends of thebridge-piece O, and through these holes screws are passed which screwinto brackets O on the frame of the instrument, thus lifting the magnetsfrom their bearing at E and relieving the strain upon the spring H. Inthe drawings one screw is shown short and the other long, so that it canbe turned from outside the case.

Although it is preferred to apply the pawl M and its ratchet M to thewhole oscillating system, as described, we may, if desired, apply it tothe pointer only, so that the magnet is free to return when the dragdiminishes, leaving the pointer in its position of maximum deflection.In suoha'case two pointers may be provided, one with a ratchet deviceand the other free to follow the movement of the magnet. Thus, as shownin Figs. 5 and 6, the face of the pointer K has secured to it one end ofa light spring-pawl N, the other end of which bears upon a ratchet O,secured to the frame of the apparatus in proximity to the face of thepointer and formed on a circular arc whose center is the pivot aboutwhich the pointer K oscillates, or, as shown in Fig. 6, the pawl may beomitted from the pointer K and the latter provided with a projection Kbearing against one side of an auxiliary pointer P, which latter isprovided with the spring-pawl N, bearing upon the ratchet O in mannerand effect as described with reference to Fig. 5, so that the auxiliarypointer P will be moved in one direction only by the pointer K andwillbe held by its springratchet at the farthest point to which it ismoved and will thus indicate the maximum deflections only. Obviously thefriction between the spring N and the curved metallic sector 0 could besuch as to render unnecessary the use of teeth on the sector.

It is to be understood that the details of this meter may be variedwithout departing from the spirit of the invention, which may be asthose in which the action depends upon an oscillating movement insteadof a revolving motion. Again, although it is convenient to use twomagnets coupled by a bridge-piece, as herein described, yet a singlemagnet or more than two magnets may, if desired, be used. Further,although it is preferred to pivot the revolving disk and the magneticbrake about parallel axes it is possible to pivot them so that theiraxes are coincidentsay by arranging the magnet so that it is supportedbeneath the center of rotation of the disk.

We claim- 1. The combination in an electric meter of a revolvingconductor, a pivoted or suspended magnetic brake and means to preventexcessive angular movement of the brake, substantially as and for thepurpose set forth.

2. In an electric meter the combination of a pivoted or suspendedmagnetic brake comprising one or more magnets, a conductor moving in themagnetic field of the brake, means for controlling the motion ofthebrake, and an indicator for multiplying and exhibiting the amount ofsuch motion, substantially as set forth.

3. In an electric meter the combination of a revolving conductor with amagnetic brake pivoted or suspended about an axis parallel to the axisof rotation of the conductor means for controlling the motion of thebrake, and an indicator for multiplying and exhibiting the amount ofsuch motion, substantially as set forth.

4. In an electric meter the combination of a pivoted magnetic systemcomprising a plurality of magnets connected by a bridge-piece, aconducting-disk revolving between the poles of the magnets about an axisparallel to the axis about which the magnetic system is pivoted, aspring controlling the motion of the magnets, a pointer for exhibitingin a multiplied form the amount of such motion, an ad justable armsecured to the axle bearing the magnets and operatively connecting suchaxle with the pointer, a pivoted pawl, and a fixed rack with which thepawl engages, substantially as and for the purpose set forth.

5. In an electric meter the combination with a pivoted magnetic brake offixed supports, and means for clamping the magnetic brake to thesupports for the purpose set forth.

In testimony whereof we have hereunto set our hands in the presence ofthe two subscribing witnesses.

JOHN HENRY BARKER. JAMES ALFRED EWING. Witnesses:

ALFRED J. BOULT, HARRY B. BRIDGES.

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